Method for changing states of electrochromic film

ABSTRACT

The disclosure relates generally to a method of changing an optical state of an electrochromic film. The electrochromic film may have a plurality of optical states. The method may include selecting a desired state of the plurality of optical states; injecting electric charges into the electrochromic film; monitoring an amount of the electric charges injected into the electrochromic film; and stopping injecting the electric charges when the electric charges reaches a pre-set amount corresponding to the desired state.

CROSS-REFERENCE To RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.16/747,353, filed on Jan. 20, 2022, which is a Continuation-in-Part ofU.S. patent application Ser. No. 15/913,669, filed on Mar. 6, 2018,issued as U.S. Pat. No. 10,539,851. The contents of all theabove-identified applications are incorporated herein by reference intheir entirety.

TECHNICAL FIELD

The present disclosure relates generally to electrochromic films, and inparticular, to methods for changing states of electrochromic films.

BACKGROUND

Electrochromism is a phenomenon displayed by some materials ofreversibly changing optical properties by using bursts of charges tocause electrochemical redox (reduction and oxidation) reactions inelectrochromic materials. The optical properties may includetransmittance, reflectance, absorptance, emittance, and color. Inparticular, electrochromic materials exhibit reversible color changes.The optical state of an electrochromic material depends on the amount ofcharge injected or extracted. The optical state of an electrochromicfilm may refer to lightness, transparency, color, reflectance, etc. Theelectrochromic film's optical state could he set at any state bycontrolling the amount of charges. In an application of smart windows,electrochromic films are integrated with the glass window to becomeserviceable. Electric controllers are used to control the electrochromicfilms integrated with glass windows (i.e., smart windows). Additionally,a color of the electrochromic films may change based on a change in thetransmittance of the electrochromic films, or degrade or change overtime as a result of electrochemical cycling.

In this disclosure, we propose different methods for changing opticalstates of electrochromic materials such as electrochromic films. Wefurther propose different devices and methods for adjusting a color ofsmart windows comprising the electrochromic materials, for example, tocompensate for a change in the transmittance of the electrochromicfilms, or electrochromic cycling. We further propose different devicesand methods of supplying power to a controller of the smart windowswhile determining a transmittance of the electrochromic films.

SUMMARY

One aspect of the present disclosure is directed to a method of changingan optical state of an electrochromic film. The electrochromic film mayhave a plurality of optical states. The method may include selecting adesired state of the plurality of optical states; injecting electriccharges into the electrochromic film; monitoring an amount of theelectric charges injected into the electrochromic film; and stoppinginjecting the electric charges when the electric charges reaches apre-set amount corresponding to the desired state.

Another aspect of the present disclosure is directed to another methodof changing an optical state of an electrochromic film. Theelectrochromic film may have a plurality of optical states. The methodmay include selecting a desired state of the plurality of opticalstates; extracting electric charges from the electrochromic film;monitoring an amount of the electric charges extracted from theelectrochromic film; and stopping extracting the electric charges whenthe electric charges reaches a pre-set amount corresponding to thedesired state.

Another aspect of the present disclosure is directed to another methodof changing an optical state of an electrochromic film. The method mayinclude setting a plurality of pre-determined optical states of theelectrochromic film; determining an amount of electric chargescorresponding to each of the plurality of pre-determined optical states;selecting a desired state of the plurality of pre-determined opticalstates; and adjusting an amount of electric charges within theelectrochromic film to the determined amount of electric chargescorresponding to the selected desired state.

Various embodiments of the present disclosure provide a method ofchanging an optical state of an electrochromic film in an electrochromicdevice, comprising determining a color of the electrochromic film;determining an amount of adjustment to be applied to the color; andcontrolling an amount of electric charges injected into and removed fromthe electrochromic film based on the determined amount of adjustment.

In some embodiments, the determining an amount of adjustment to beapplied to the color further comprises determining a difference betweenthe color and a target color of the electrochromic film. In someembodiments, the target color is a color of an electrochromic film inanother electrochromic device in a same room, house, building, ordwelling. In some embodiments, the target color is preset to be a samecolor for all electrochromic films in other electrochromic devices in asame room, house, building, or dwelling. In some embodiments, the targetcolor is a color of the electrochromic film when the electrochromic filmis in a dark state and an undegraded state. In some embodiments, thetarget color is a color of the electrochromic film when theelectrochromic film is in a light state and an undegraded state. In someembodiments, the determining an amount of adjustment to be applied tothe color further comprises: determining whether the difference isgreater than a threshold amount; and in response to determining that thedifference is greater than the threshold amount, injecting or removingelectric charges into the electrochromic film until the difference isless than the threshold amount. In some embodiments, the controlling anamount of electric charges injected into and removed from theelectrochromic film comprises injecting or removing an amount ofelectric charges determined to obtain the target color of theelectrochromic film. In some embodiments, the determining a color of theelectrochromic film comprises: determining a transmittance state of theelectrochromic film; and determining the color of the electrochromicfilm based on the determined transmittance state, and based on arelationship between the transmittance state and the color of theelectrochromic film. In some embodiments, the determining an amount ofadjustment to be applied to the color further comprises: determining theamount of adjustment to be applied to the color based on a rate ofchange of the color relative to a change in the transmittance state. Insome embodiments, the controlling an amount of electric charges injectedinto and removed from the electrochromic film comprises applying anexternal DC voltage to the electrochromic film. In some embodiments, thecontrolling an amount of electric charges injected into and removed fromthe electrochromic film comprises applying an external DC current to theelectrochromic film. In some embodiments, the controlling an amount ofelectric charges injected into and removed from the electrochromic filmcomprises applying an external pulsed voltage to the electrochromicfilm. In some embodiments, the controlling an amount of electric chargesinjected into and removed from the electrochromic film comprisesapplying an external pulsed current to the electrochromic film. In someembodiments, the controlling an amount of electric charges injected intoand removed from the electrochromic film comprises applying acombination of an external voltage and an external current to theelectrochromic film.

In some embodiments, the determining a color of the electrochromic filmcomprises determining a color reflected by the electrochromic film ordetermining a color transmitted by the electrochromic film. In someembodiments, the determining a color of the electrochromic filmcomprises determining one or more of a transmitted color and a reflectedcolor. In some embodiments, the determining a color of theelectrochromic film comprises determining a refracted color.

In some embodiments, the method further comprises directly preinstallingthe electrochromic device into a window frame.

Various embodiments of the present disclosure provide a method ofchanging an optical state of an electrochromic film in an electrochromicdevice, comprising detecting a light intensity of external light; andadjusting a level of transmission of the electrochromic film based onthe detected light intensity or a change in the detected lightintensity.

In some embodiments, the method further comprises detecting the lightintensity simultaneously with providing a power to the electrochromicdevice. In some embodiments, the detecting a light intensity comprises:determining an amount of current generated during a process of providingthe power; and detecting the light intensity based on the determinedamount of current generated. In some embodiments, the detecting thelight intensity based on the determined amount of current generatedcomprises detecting the light intensity based on a linear relationshipbetween the light intensity and the amount of current generated.

Other objects, features and advantages of the described embodiments willbecome apparent to those skilled in the art from the following detaileddescription. It is to be understood, however, that the detaileddescription and specific examples, while indicating preferredembodiments of the present invention, are given by way of illustrationand not limitation. Many changes and modifications within the scope ofthe present invention may be made without departing from the spiritthereof, and the invention includes all such modifications.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred and non-limiting embodiments of the invention may be morereadily understood by referring to the accompanying drawings in which:

FIG. 1 is a graphical presentation illustrating a simplified schematicof an electrochromic device, consistent with exemplary embodiments ofthe present disclosure.

FIG. 2 is a sectional view of a simplified schematic of anelectrochromic device comprising a solid polymer electrolyte therein,consistent with exemplary embodiments of the present disclosure.

FIG. 3 is a graphical presentation illustrating a controller, consistentwith exemplary embodiments of the present disclosure.

FIG. 4 is a graph illustrating a response of an exemplary electrochromicfilm changing from a dark state to a clear state under a constantvoltage, consistent with exemplary embodiments of the presentdisclosure.

FIG. 5 is a graph illustrating dependence of transmission of anexemplary electrochromic film on the amount of injected charges under aconstant voltage, consistent with exemplary embodiments of the presentdisclosure.

FIG. 6 is a graph illustrating a response of an exemplary electrochromicfilm changing from a clear state to a dark state under a constantvoltage, consistent with exemplary embodiments of the presentdisclosure.

FIG. 7 is a graph illustrating dependence of transmission of anexemplary electrochromic film on the amount of extracted charges under aconstant voltage, consistent with exemplary embodiments of the presentdisclosure.

FIG. 8 is a graph illustrating a response of an exemplary electrochromicfilm changing from a dark state to a clear state under a constantcurrent, consistent with exemplary embodiments of the presentdisclosure.

FIG. 9 is a graph illustrating dependence of transmission of anexemplary electrochromic film on the amount of injected charges under aconstant current, consistent with exemplary embodiments of the presentdisclosure.

FIG. 10 is a graph illustrating a response of an exemplaryelectrochromic film changing from a clear state to a dark state under aconstant current, consistent with exemplary embodiments of the presentdisclosure.

FIG. 11 is a graph illustrating dependence of transmission of anexemplary electrochromic film on the amount of extracted charges under aconstant current, consistent with exemplary embodiments of the presentdisclosure.

FIGS. 12A, 12B, 13A, and 13B are schematic illustrations of anelectrochromic device (e.g., a smart window), consistent with exemplaryembodiments of the present disclosure.

FIG. 14 is a graph showing an exemplary relationship between changes incolor of an exemplary electrochromic device and changes in transmittancefrom a clear state to a dark state under a constant current.

FIG. 15 is a schematic illustration of an exemplary tristimuluscolorimeter.

FIG. 16 is a schematic illustration of an electrochromic device (e.g., asmart window), consistent with exemplary embodiments of the presentdisclosure.

FIGS. 17-18 are diagrams illustrating a self-contained and self-poweredcontroller powered by an energy generator such as a solar cell.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Specific, non-limiting embodiments of the present invention will now bedescribed with reference to the drawings. It should be understood thatparticular features and aspects of any embodiment disclosed herein maybe used and/or combined with particular features and aspects of anyother embodiment disclosed herein. It should also be understood thatsuch embodiments are by way of example and are merely illustrative ofbut a small number of embodiments within the scope of the presentinvention. Various changes and modifications obvious to one skilled inthe art to which the present invention pertains are deemed to be withinthe spirit, scope and contemplation of the present invention as furtherdefined in the appended claims.

Unless the context requires otherwise, throughout the presentspecification and claims, the word “comprise” and variations thereof,such as, “comprises” and “comprising” are to be construed in an open,inclusive sense, that is as “including, but not limited to”. Numericranges are also inclusive of the numbers defining the range.Additionally, the singular forms “a”, “an” and “the” include pluralreferents unless the context clearly dictates otherwise.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure or characteristicdescribed in connection with the embodiment is included in at least oneembodiment of the present invention. Thus, the appearances of thephrases “in one embodiment” or “in an embodiment” in various placesthroughout this specification are not necessarily all referring to thesame embodiment, but may be in some instances. Furthermore, theparticular features, structures, or characteristics may be combined inany suitable manner in one or more embodiments.

Electrochromic materials are commonly used in electrochromic devices.FIG. 1 is a graphical illustration showing a simplified schematic of anelectrochromic device 100 (e.g., a smart window), consistent withexemplary embodiments of the present disclosure. The electrochromicdevice 100 may include two layers of glass 101, two adhesive layers 102,an electrochromic film 103, one or more electric wires 104, and acontroller 105 (as shown in FIG. 3).

The electrochromic film 103 may be sandwiched between the two layers ofglass 101. The adhesive layers 102 are configured to attached theelectrochromic film 103 to the layers of glass 101. The integration ofthe electrochromic film 103 with the window (layers of glass 101) isdescribed in details in U.S. patent application Ser. No. 15/399,852,which is incorporated herein by reference. In some examples, theelectrochromic film 103 may be attached to an outer layer of the glass101 and/or fastened to the glass 101, for example, via a frame. In someexamples, the electrochromic device 100 may be directly preinstalledinto a window frame.

One end 104 a of the electric wires 104 is electrically connected to theelectrochromic film 103. The other end 104 b of the electric wires 104is electrically connected to the controller 105. The controller 105 maybe configured to control the state of the electrochromic device 100 bycontrolling the states of the electrochromic film 103. The controller105 may be placed outside the glass 101, or laminated between the twolayers of glass 101 similar to the electrochromic film 103.

In some embodiments, the adhesive layers 102 may include a polymericmaterial, particularly a thermosetting polymer material. Suitablethermoset polymer materials may include, but are not limited to,polyvinyl butyral (PVB), ethylene-vinyl acetate (EVA), polyurethanes,etc. In some embodiments, the two adhesive layers may comprise amaterial that not only is configured to bond the electrochromic filmthereto, but is also transparent. The two adhesive layers may comprisethe same materials or different materials.

The electrochromic film 103 comprises a solid electrolyte disposedtherein, according to one embodiment. The detailed structure of theelectrochromic film 103 is shown in FIG. 2 and described in detailbelow.

The exemplary electrochromic device 100 shown in FIG. 1 can be theelectrochromic devices described in the specification and shown in theother figures.

As shown in FIG. 2, the electrochromic film 103 may include a firsttransparent electrically conductive film 1312 and a second transparentelectrically conductive film 1310. The first and second electricallyconductive films 1312, 1310 may have the same or different dimensions,comprise the same or different material, etc. In some embodiments, thefirst and second transparent electrically conductive films may beadhesive films as shown in FIG. 1. In some other embodiments, the firstand second transparent electrically conductive films may be additionalfilms. The first and second electrically conductive films 1312, 1310 mayalso each independently have a single layer or multilayer structure.Suitable material for the first and second electrically conductive films1312, 1310 may include, but is not limited to, tin doped indium oxide(ITO), fluorine doped indium oxide, antimony doped indium oxide, zincdoped indium oxide, aluminum doped zinc oxide, silver nano wire, metalmesh, combinations thereof, and/or other such transparent materialexhibiting sufficient electrical conductance. In preferred aspects, thefirst and second electrically conductive films 1312, 1310 may compriseITO.

As further shown in FIG. 2, a layer 1314 of electrochromic material isdeposited on an interior surface 1316 of the first electricallyconductive film 1312. The layer 1314 of electrochromic material isconfigured to effect a reversible color change upon reduction (gain ofelectrons) or oxidation (loss of electron) caused by an electricalcurrent. In some embodiments, the layer 1314 of electrochromic materialmay be configured to change from a transparent state to a colored state,or from a colored state to another colored state, upon oxidation orreduction. In some embodiments, the layer 1314 of electrochromicmaterial may be a polyelectrochromic material in which more than tworedox states are possible, and may thus exhibit several colors.

In some embodiments, the layer 1314 of electrochromic material maycomprise an organic electrochromic material, an inorganic electrochromicmaterial, a mixture of both, etc. The layer 1314 of electrochromicmaterial may also be a reduction colored material (i.e., a material thatbecomes colored upon acquisition of electrons), or an oxidation coloredmaterial (i.e., a material that becomes colored upon the loss ofelectrons).

In some embodiments, the layer 1314 of electrochromic material mayinclude a metal oxide such as MoO₃, V₂O₅, Nb₂O₅, WO₃, TiO₂, Ir(OH)_(x),SrTiO₃, ZrO₂, La₂O₃, CaTiO₃, sodium titanate, potassium niobate,combinations thereof, etc. In some embodiments, the layer 1314 ofelectrochromic material may include a conductive polymer such aspoly-3,4-ethylenedioxy thiophene (PEDOT), poly-2,2′-bithiophene,polypyrrole, polyaniline (PANT), polythiopene, polyisothianaphthene,poly(o-aminophenol), polypyridine, polyindole, polycarbazole,polyquinone, octacyanophthalocyanine, combinations thereof, etc.Moreover, in some embodiments, the layer 1314 of electrochromic materialmay include materials, such as viologen, anthraquinone, phenocyazine,combinations thereof, etc. Additional examples of electrochromicmaterials, particularly those including multicolored electrochromicpolymers, may be found in U.S. Patent Application No. 62/331,760, filedMay 4, 2016, titled Multicolored Electrochromic Polymer Compositions andMethods of Making and Using the Same, and U.S. patent application Ser.No. 15/399,839, filed on Jan. 6, 2017, titled MulticoloredElectrochromic Polymer Compositions and Methods of Making and Using theSame. The entirety of the above-referenced two applications are hereinincorporated by reference.

As additionally shown in FIG. 2, a charge storage layer 1318 isdeposited on an interior surface 1320 of the second electricallyconductive film 1310. Suitable materials for the charge storage layer1318 may include, but are not limited to, vanadium oxide, binary oxides(e.g., CoO, IrO₂, MnO, NiO, and PrO_(x)), ternary oxides (e.g.,Ce_(x)V_(y)O_(z)), etc.

In some embodiments, the charge storage layer 1318 may be replaced withan optional second layer of electrochromic material. This optionalsecond layer of electrochromic material may have the same or differentdimensions, comprise the same or different composition, etc., as thefirst layer 1314 of electrochromic material.

The electrochromic film 103 also includes an electrolyte layer 1322positioned between the layer 1314 of electrochromic material and thecharge storage layer 1318. In some embodiments, the electrolyte layer1322 may include a liquid electrolyte as known in the art. In someembodiments, the electrolyte layer 1322 may include a solid stateelectrolyte, including but not limited to, Ta₂O₅, MgF, Li₃N, LiPO₄,LiBO₂—Li₂SO₄, etc. In some embodiments, the electrolyte layer 1322 mayinclude a polymer based electrolyte comprising an electrolyte salt(e.g., LiTFSI, LiPF₆, LiBF₄, LiClO₄, LiCF₃SO₃, LiN(CF₃SO₂)₂, LiSbFg,LiAsF₆, LiN(CF₃CF₂SO₂)₂, (C₂H₅)₄NBF₄, (C₂H₅)₃CH₃NBF₄, LiI, etc.), apolymer matrix (e.g., polyethylene oxide, poly(vinylidenefluoride(PVDF), poly(methyl methacrylate) (PMMA), polyethylene oxide(PEO), poly(acrylonitrile) (PAN), polyvinyl nitrile, etc.), and one ormore optional plasticizers (e.g., glutaronitrile, succinonitrile,adiponitrile, fumaronitrile, etc.).

In some embodiments, the electrolyte layer 1322 comprises a solidpolymer electrolyte. In one embodiment, the solid polymer electrolytecomprises a polymer framework, at least one solid plasticizer, and atleast one electrolyte salt. In some embodiments, the polymer frameworkmay include a polar polymer material having an average molecular weightof about 10,000 Daltons or greater. In particular embodiments, the polarpolymer material may have an average molecular weight in a range fromabout 10,000 Daltons to about 800,000,000 Daltons. In some embodiments,the polar polymer material may be present in an amount ranging fromabout 15 wt. % to about 80 wt. % based on the total weight of the solidpolymer electrolyte.

The aforementioned polar polymer material may include one or more polarpolymers, each of which may include one or more of: C, N, F, O, H, P, F,etc. Suitable polar polymers may include, but are not limited to,polyethylene oxide, poly(vinylidene fluoride-hexafluoropropylene,poly(methyl methacrylate), polyvinyl nitrile, combinations thereof, etc.In embodiments where a plurality of polar polymers is present, thepolymers may be crosslinked to form a network having enhanced mechanicalproperties.

The polar polymer material may have a sufficient amorphicity so as toachieve sufficient ion conductivity. Amorphous polymer materialstypically exhibit high ion conductivities. Accordingly, in someembodiments, the polar material disclosed herein may have an amorphous,or a substantially amorphous, microstructure.

In some embodiments, the polar polymer material may have asemi-crystalline or crystalline microstructure. In such cases, variousmodifications may be implemented with respect to the polymer material tosuppress the crystallinity thereof. For instance, one modification mayinvolve use of branched polar polymers, linear random copolymers, blockcopolymers, comb polymers, and/or star-shaped polar polymers. Anothermodification may include incorporation of an effective amount of solidplasticizers in the polar polymer material, as discussed in greaterdetail below.

Various properties of the polar polymer material also may be selectedand/or modified to maximize ion conductivity. These properties mayinclude, but are not limited to, glass transition temperature, segmentalmobility/flexibility of the polymer backbone and/or any side chainsattached thereto, orientation of the polymers, etc.

As noted above, the presently disclosed solid electrolyte may include atleast one solid plasticizer. The at least one solid plasticizer may besubstantially miscible in the polymer framework of the solidplasticizer. The at least one solid plasticizer may include an organicmaterial (e.g., small, solid organic molecules) and/or an oligomericpolymer material, in some embodiments. In various embodiments, the atleast one solid plasticizer may be selected from the group includingglutaronitrile, succinonitrile, adiponitrile, fumaronitrile, andcombinations thereof.

In some embodiments, a plurality of solid plasticizers may be present inthe polymer framework, where each plasticizer may independently includean organic material (e.g., small, solid organic molecules) and/or anoligomeric polymer material. Particularly, each plasticizer mayindependently be glutaronitrile, succinonitrile, adiponitrile,fumaronitrile, etc. Moreover, the dimensions of at least two, some, amajority, or all of the plasticizers may be the same or different as oneanother.

In some embodiments, the total amount of solid plasticizer may be in arange from about 20 wt. % to about 80 wt. % based on the total weight ofthe solid electrolyte.

As additionally noted above, the solid polymer electrolyte may includeat least one electrolyte salt. In some embodiments, the at least oneelectrolyte salt may comprise an organic salt. In some embodiments, theat least one electrolyte salt may comprise an inorganic salt. Suitableelectrolyte salts may include, but are not limited to, LiTFSI, LiPF₆,LiBF₄, LiClO₄, LiCF₃SO₃, LiN(CF₃SO₂)₂, LiSbFg, LiAsF₆, LiN(CF₃CF₂SO₂)₂,(C₂H₅)₄NBF₄, (C₂H₅)₃CH₃NBF₄, LiI, combinations thereof, etc. In someembodiments, the total amount of electrolyte salt may be in a range fromabout 10 wt. % to about 50 wt. % based on the total weight of the solidelectrolyte.

The solid polymer electrolyte is distinguishable from conventionalliquid electrolytes, as well as gel polymer electrolytes including anionic liquid therein. In other words, the presently disclosed solidpolymer electrolyte may be an all solid polymer electrolyte, and doesnot include any liquid or gel components therein. The presentlydisclosed solid polymer electrolyte may also be transparent in someaspects. Additionally, the solid polymer electrolyte may have an ionconductivity in a range from about 10⁻⁷ S/cm to about 10⁻³ S/cm.

Methods of making the presently disclosed solid polymer electrolyte mayinclude synthesis, polymerization, solvation, etc. processes as known inthe art. In one particular, non-limiting embodiment, a method of makingthe presently disclosed polymer electrolyte may include: (a) combiningthe polymer framework, the at least one plasticizer, and the at leastone electrolyte salt in an appropriate solvent; and (b) removing thesolvent to obtain the solid polymer electrolyte. Exemplary solvents mayinclude, but are not limited to, acetone, methanol, tetrahydrofuran,etc. In some embodiments, one or more experimental parameters may beoptimized to facilitate the dissolving of the polymer framework,plasticizer, and electrolyte salt in the solvent. These experimentalparameters may include the components remain in the solvent,agitation/stirring of the solvent, etc.

In some embodiments, the electrolyte layer 1322 of FIG. 2 comprises asolid polymer electrolyte, such as the solid polymer electrolytesdescribed above, and does not include any liquid or gel electrolyte.Such a solid polymer electrolyte (i) has sufficient mechanical strengthyet is versatile in shape so as to allow easy formation into thin films,and thin-film shaped products; (ii) avoids issues related to adhesionand print processing affecting conventional electrolytes; (iii) providesstable contact between the electrolyte/electrode interfaces (those withand without the electrochromic material coating thereon); (iv) avoidsthe problem of leakage commonly associated with liquid electrolytes; (v)has desirable non-toxic and non-flammable properties; (vi) avoidsproblems associated with evaporation due to its lack of vapor pressure;(vii) exhibits improved ion conductivities as compared to conventionpolymer electrolytes; etc.

Additional examples of electrolyte materials, particularly thoseincluding solid polymer electrolytes, may be found in U.S. PatentApplication No. 62/323,407, filed Apr. 15, 2016, titled Solid PolymerElectrolyte for Electrochromic Devices, and U.S. patent application Ser.No. 15/487,325, filed on Apr. 13, 2017, titled Solid Polymer Electrolytefor Electrochromic Devices. The entirety of the above-referenced twoapplications are herein incorporated by reference.

The electrochromic film 103 may be used in various applications and/orin permutations, which may or may not be noted in the illustrativeembodiments/aspects described herein. For instance, the electrochromicfilm 103 may include more or less features/components than those shownin FIG. 2, in some embodiments. Additionally, unless otherwisespecified, one or more components of the electrochromic film 103 may beof conventional material, design, and/or fabricated using knowntechniques (e.g., sputtering, chemical vapor deposition (CVD), physicalvapor deposition (PVD), plasma-enhanced chemical vapor deposition(PECVD), spray coating, slot-die coating, dip coating, spin coating,printing, etc.), as would be appreciated by skilled artisans uponreading the present disclosure.

FIG. 3 is a graphical presentation illustrating a controller 105,consistent with exemplary embodiments of the present disclosure. Thecontroller 105 may include a power converter 301, a power output control302, and a signal receiver 303. The power converter 301 may convertinput power from a power source to the power required by the signalreceiver 303 and the power output control 302. The power source could beeither a power source integrated with the controller 105 as aself-contained, self-powered unit, or an external power source, providedby, for example, power of a building where the electrochromic device isinstalled. The power output control 302 may be configured to supplypower to the electrochromic film 103. In particular, the power output302 may be configured to supply voltage between the first and secondelectrically conductive films 1312, 1310. Since the state of theelectrochromic film 103 is driven by electric charges, the power outputcontrol 302 can inject into or extract a certain amount of electriccharges from the electrochromic film 103 based on the signals the signalreceiver 303 receives, in order to change the state of theelectrochromic film 103. The signal receiver 303 may be configured toreceive signals sent to the controller 105, and transfer the signals tothe power output control 302. In some embodiments, the signal receiver303 may be connected to an external switch and a central switch toprovide both local and global controls of the electrochromic device 100.

In the present application, we propose different methods for changingoptical states of electrochromic materials. The optical states ofelectrochromic materials can be changed by injecting or extractingelectric charges into the electrochromic films. Both voltage driving andcurrent driving can be employed to inject/extract electric charges. Inaddition, the combination of voltage driving and current driving canalso be employed. Further, the voltage driving and the current drivingcan be operated at either direct current (DC) or alternating current(AC). As long as the required amount of electric charges are injected orextracted, the electrochromic film can be set at a certain opticalstate.

Changing Electrochromic Film's Optical State by Voltage Driving

In one embodiment, changing the optical state of an electrochromic filmcan be operated by a DC voltage. An external power supply outputs aconstant voltage to the electrochromic film. The current through thefilm and the film's light transmission can be monitored over time. Byapplying the constant voltage, the charges are injected into theelectrochromic film, inducing oxidation of the film, thereby changingits optical state.

Example 1

An exemplary electrochromic film is operated under a constant voltage of1.5 V. FIG. 4 presents the response of the electrochromic film changingfrom a dark state (with minimum transmission) to a clear state (withmaximum transmission) under a constant voltage. As shown in FIG. 4, thecurrent density of electrochromic film continues decreasing over time,while the transmission of the electrochromic film increases as thevoltage applied and becomes saturated after 20 s. This may indicate thatthe electrochromic film only requires certain amount of charges tochange its state.

FIG. 5 shows dependence of the transmission of the electrochromic filmon the amount of injected charges under a constant voltage of 1.5 V. Thetransmission of the electrochromic film increases as the amount ofinjected charges increases. By controlling the amount of the chargesinjected into the electrochromic film, the transmission of theelectrochromic film can be adjusted accordingly. Thus, the transmissionof the electrochromic film can be set at any state by injecting acertain amount of charges. For example, if the transmission of theelectrochromic film is to be set at 40% from the dark state, a chargedensity of about 3 mC/cm² is needed to inject into the electrochromicfilm.

In another embodiment, to change the state of an electrochromic filmfrom a clear state back to a dark state, the polarity of the externalvoltage can be switched. By switching the polarity of the externalvoltage, the charges can be extracted from the electrochromic film,inducing reduction of the electrochromic film, thereby changing itsstate.

Example 2

Another exemplary electrochromic film is operated under a constantvoltage of 1 V, as shown in FIGS. 6-7. FIG. 6 presents the response ofthe exemplary electrochromic film changing from a clear state (withmaximum transmission) to a dark state (with minimum transmission) undera constant voltage. As shown in FIG. 6, negative current densityindicates that the charge is extracted from the electrochromic film. Asthe current density drops to zero, the transmission of theelectrochromic film decreases from the maximum to the minimum.

FIG. 7 shows dependence of the transmission of the electrochromic filmon the amount of extracted charges under a constant voltage. Thetransmission of the electrochromic film decreases as the amount ofextracted charges increases. By controlling the amount of chargesextracted from the electrochromic film, the transmission of theelectrochromic film can be adjusted accordingly. The transmission of theelectrochromic film can be set at any state by extracting a certainamount of charges. For example, if the transmission of theelectrochromic film is to be set at 35% from the clear state, a chargedensity of about 4 mC/cm² should be set in the electrochromic film.

Changing Electrochromic Film's Optical State by Current Driving

In another embodiment, changing the optical state of an electrochromicfilm can be operated by constant DC current. An external power supplyoutputs a constant current to the electrochromic film. The currentthrough the film and the film's transmission can be monitored over time.By applying the constant current, the charges are injected into theelectrochromic film, inducing oxidation of the film, thereby changingits optical state.

Example 3

Another exemplary electrochromic film is operated under a constantcurrent of 0.06 mA/cm², as shown in FIGS. 8-9. FIG. 8 presents theresponse of the exemplary electrochromic film changing from a dark state(with minimum transmission) to a clear state (with maximum transmission)under a constant current. As shown in FIG. 8, the transmission of theelectrochromic film changes as the constant current supplied, andbecomes saturated after around 70 s. The constant current sharply dropsnear when the film's transmission reaches the maximum. Since the amountof the charges injected equals the current times the time, this mayindicate that after the state of the electrochromic film is totallyswitched from a clear state to a dark state, there's no need for anyadditional charge injection. Thus, by controlling the amount of thecharges injected, the transmission of the electrochromic film can beadjusted.

FIG. 9 shows dependence of the transmission of the electrochromic filmon the amount of the injected charges under a constant current. Thetransmission of the electrochromic film increases as the amount of theinjected charges increases. By controlling the amount of chargesinjected into the electrochromic film, the transmission ofelectrochromic film can be adjusted accordingly. The transmission of theelectrochromic film can be set at any state by injecting a certainamount of charges. For example, if the transmission of electrochromicfilm is to be set at 50% from the dark state, a charge density of about3 mC/cm² is needed to inject into the electrochromic film.

In another embodiment, to change the state of an electrochromic filmfrom a clear state back to a dark state, the polarity of the externalcurrent can be switched. By switching the polarity of the externalcurrent, the charges can be extracted from the electrochromic film,inducing reduction of the electrochromic film, thereby changing itsstate.

Example 4

Another exemplary electrochromic film is operated under a constantcurrent of 0.06 mA/cm², as shown in FIGS. 10-11. FIG. 10 presents theresponse of the exemplary-electrochromic film changing from a clearstate (with maximum transmission) to a dark state (with minimumtransmission) under a constant current. As shown in FIG. 10 negativecurrent density indicates that the charge is extracted from theelectrochromic film. The transmission of the electrochromic film changesas the constant current supplied. The constant current sharply dropsnear when the transmission of the electrochromic film reaches theminimum. Since the amount of charges extracted equals the current timesthe time, this may indicate that after the state of the electrochromicfilm is totally switched from the clear state to the dark state, there'sno need for any additional charge extraction. Thus, by controlling theamount of the charges extracted, the transmission of the electrochromicfilm can be adjusted.

FIG. 11 shows dependence of the transmission of the electrochromic filmon the extracted charges under a constant current. The transmission ofthe electrochromic film decreases as the amount of the extractedincreases. By controlling the amount of charges extracted from theelectrochromic film, the transmission of the electrochromic film can beadjusted accordingly. The transmission of the electrochromic film can beset at any state by extracting a certain amount of charges. For example,if the transmission of the electrochromic film is to be set at 40% fromthe clear state, a charge density of about 3 mC/cm² should be set in theelectrochromic film.

FIGS. 12A, 12B, 13A, and 13B illustrate schematics of electrochromicdevices 1200 and 1300 (e.g., a smart window), respectively, consistentwith exemplary embodiments of the present disclosure. In FIGS. 12A, 12B,13A, and 13B, a color of the electrochromic devices 1200 and 1300 may bemonitored and/or changed. In some embodiments, a color of theelectrochromic devices 1200 and 1300 may refer to a color ofelectrochromic films (e.g., 1203, 1303) in the electrochromic devices1200 and 1300.

FIG. 12A is an illustration showing a schematic of an electrochromicdevice 1200 (e.g., a smart window), consistent with exemplaryembodiments of the present disclosure. The electrochromic device 1200may include two layers of glass 1201, two adhesive layers 1202, anelectrochromic film 1203, one or more electric wires 1204, a controller1205, and a color sensor 1206 integrated into the electrochromic device1200. In some embodiments, the color sensor 1206 may be implemented as aspectrometer and/or a tri stimulus colorimeter such as a tristimuluscolorimeter described with respect to FIG. 15.

In some embodiments, the controller 1205 may comprise a signal receiverconfigured to receive a current color information of color coordinatesor color dimensions of the electrochromic device 1200 from the colorsensor 1206, and compare the received color information to a targetcolor. The controller 1205 may adjust a current color of theelectrochromic device 1200 to the target color based on a differencebetween current color information and the target color. In someexamples, the controller 1205 may adjust a current color of theelectrochromic device 1200 to be closer to the target color. Forexample, the controller 1205 may adjust a current color of theelectrochromic device 1200 to be within a predetermined threshold fromthe target color. In some examples, the controller 1205 may adjust acurrent color of the electrochromic device 1200 if the current colordiffers from the target color by more than a predetermined threshold,and may not adjust a current color of the electrochromic device 1200 ifthe current color differs from the target color by less than or equal toa predetermined threshold. In some examples, the controller 1205 mayreceive information of the target color by a global control. In someexamples, the target color may be a baseline color of the electrochromicdevice 1200 at a dark state, at a clear state, or any transmittancestate. Additionally or alternatively, in some examples, the target colormay be a color of the electrochromic device 1200 that has not undergoneelectrochromic degradation or cycling (e.g., in an undegraded state). Insome examples, the target color may be predetermined based on a color ofone or more other windows in a same room, house, building, or dwelling.For example, the target color may be a same color as that of one or moreother windows in a same room, house, building, or dwelling. In someexamples, the target color may be preset to be a same color for allwindows in a same room, house, building, or dwelling.

In some examples, the controller 1205 may determine the colorinformation based on a transmittance state of the electrochromic device1200. For example, the controller 1205 may determine information of anoptical state, for example, a transmittance state, of the electrochromicdevice 1200, such as whether the electrochromic device 1200 is in a dearstate, a dark state, or somewhere in between a clear state and darkstate, using a spectrometer and/or a tristimulus colorimeter. Thecontroller 1205 may determine color coordinates of the electrochromicdevice 1200 based on a transmittance state and a predeterminedrelationship between color coordinates and a transmittance state of theelectrochromic device 1200, such as a relationship 1400 as shown in FIG.14. In some examples, the controller 1205 may further determine a rateof change of the color coordinates relative to a change in transmittancestate and/or a stage of transmission of the electrochromic device 1200.The controller 1205 may determine an amount of adjustment needed basedon the determined rate of change, and an amount of charges to beinjected or withdrawn. For example, the controller 1205 may determinethat the electrochromic device 1200 may be in a first stage (e.g., 1406in FIG. 14), a second stage (e.g., 1408 in FIG. 14), a third stage(e.g., 1410 in FIG. 14), or a fourth stage (e.g., 1412 in FIG. 14), asdescribed with reference to FIG. 14. In some examples, the controller1205 may determine that the electrochromic device is in the first stage1406, and determine that in order to obtain the target color, thecontroller 1205 needs to add more red and yellow. From the determinedcolor coordinates, the controller 1205 may determine a differencebetween the determined color coordinates and target color coordinates,and adjust a color of the electrochromic device 1200 to compensate forthe difference between the determined color coordinates and the targetcolor coordinates.

In some embodiments, the controller 1205 may be configured to adjust thecolor of the electrochromic device 1200 by injecting or withdrawing acertain amount of charges into the electrochromic device 1200. Thecontroller 1205 may continuously monitor a current color of theelectrochromic device 1200, continuously gather information of thedifference between the current color and the target color, andcontinuously adjust the current color until the current color matchesthe target color or differs from the target color by less than athreshold. The controller 1205 may be configured to adjust the color ofthe electrochromic device 1200 to compensate or account for changes intransmittance state and/or electrochromic degradation of theelectrochromic device 1200.

The electrochromic film 1203 may be sandwiched between the two layers ofglass 1201. The adhesive layers 1202 are configured to attach theelectrochromic film 1203 to the layers of glass 1201. The integration ofthe electrochromic film 1203 with the window (layers of glass 1201) isdescribed in details in U.S. patent application Ser. No. 15/399,852,which is incorporated herein by reference.

One end of the electric wires 1204 may electrically connected to theelectrochromic film 1203. An other end of the electric wires 1204 may beelectrically connected to the controller 1205. The controller 1205 maybe configured to control the optical state of the electrochromic device1200 by controlling the optical states of the electrochromic film 1203.The controller 1205 may be placed outside the glass 1201, or laminatedbetween the two layers of glass 1201 similar to the electrochromic film1203.

In some embodiments, the adhesive layers 1202 may include a polymericmaterial, particularly a thermosetting polymer material. Suitablethermoset polymer materials may include, but are not limited to,polyvinyl butyral (PVB), ethylene-vinyl acetate (EVA), polyurethanes,etc. In some embodiments, the two adhesive layers may comprise amaterial that not only is configured to bond the electrochromic filmthereto, but is also transparent. The two adhesive layers may comprisethe same materials or different materials.

The electrochromic film 1203 may comprise a solid electrolyte disposedtherein, according to one embodiment. The electrochromic film 1203 maybe implemented as the electrochromic film 103 as shown in FIGS. 1 and 2.

In some embodiments, as illustrated in diagram FIG. 12B, the colorsensor 1206 may be disposed on an exterior surface of the electrochromicdevice 1200. The color sensor may comprise an active sensing portion1207. The active sensing portion 1207 may face the electrochromic device1200 rather than facing a sun in order to determine color informatione.g., color coordinates) of the electrochromic device 1200. Sun lightmay be reflected from the electrochromic device 1200, and received bythe color sensor 1206. The active sensing portion 1207 may determine areflected color from the electrochromic device 1200, The color of theelectrochromic film 1203 may include the reflected color.

FIG. 13A is an illustration showing a schematic of an electrochromicdevice 1300 (e.g., a smart window), consistent with exemplaryembodiments of the present disclosure. The electrochromic device 1300may include two layers of glass 1301, two adhesive layers 1302, anelectrochromic film 1303, one or more electric wires 1304, a controller1305, and a color sensor 1306 integrated into the electrochromic device1300.

In some embodiments, the color sensor 1306 may be implemented as aspectrometer and/or a tristimulus colorimeter such as the tristimuluscolorimeter 1300, as described above. The controller 1305 may beimplemented as the controller 1205 of FIG. 12A, The two layers of glass1301 may be implemented as the two layers of glass 1201 of FIG. 12A. Thetwo adhesive layers 1302 may be implemented as the two adhesive layers1202 of FIG. 12A. The electrochromic film 1303 may be implemented as theelectrochromic film 1203 of FIG. 12A, The one or more electric wires1304 may be implemented as the one or more electric wires 1204 of FIG.12A.

In some embodiments, as illustrated in diagram FIG. 13B, the colorsensor 1306 may be disposed on an interior surface of the electrochromicdevice 1300. The color sensor 1306 may comprise an active sensingportion 1307. The active sensing portion 1307 may face theelectrochromic device 1300 in order to determine color information(e.g., color coordinates) of the electrochromic device 1300. The sunlight may be transmitted through the electrochromic device 1300, orrefracted through the electrochromic device 1300, and received by thecolor sensor 1305. The active sensing portion 1307 may determine atransmitted color or a refracted color from the electrochromic device1300. The color of the electrochromic film may include the transmittedcolor.

FIG. 14 shows an exemplary relationship between changes in color of anexemplary electrochromic device and changes in transmittance from aclear state to a. dark state under a constant current. FIG. 14 depicts arelationship between color coordinates or color dimensions in a Labcolor space, as denoted by (a,b), and states of transmittance. Forexample, a start point 1402 represents a color coordinate or colordimension of the electrochromic device when the electrochromic device isin a clear state, or a state with full or nearly full transmittance. Thestart point 1402 indicates that a color of the electrochromic device ina clear state has a mixture of green, red, yellow, and blue, with moregreen than red and more blue than yellow. As the electrochromic devicetransforms from a clear state to a dark state, amounts of green and blueincrease while amounts of red and yellow decrease at a first stage 1406,until a second point 1407. In some embodiments, the first stage 1406extends between the start point 1402 and the second point 1407. In someembodiments, a second stage 1408 extends between the second point 1407and a third point 1409. During the second stage 1408, amounts of greenand yellow increase while amounts of blue and red decrease. In someembodiments, a third stage 1410 extends between the third point 1409 anda fourth point 1411. During the third stage 1410, amounts of red andyellow increase while amounts of green and blue decrease. In someembodiments, a fourth stage 1412 extends between the fourth point 1411and an end point 1404. During the fourth stage 1412, amounts of blue andred increase while amounts of green and yellow decrease. The end point1404 represents a color coordinate or color dimension of theelectrochromic device when the electrochromic device is in a dark state,or a state with little to no transmittance. In some embodiments, arelationship between color coordinates or color dimensions in a Labcolor space and states of transmittance may be based on a level ofelectrochromic cycling, or a level or electrochromic degradation due tothe electrochromic cycling. For example, a color coordinate at a clearstate, or a color coordinate at a dark state, may change based on alevel of electrochromic cycling.

If an electrochromic device is transitioning between a dark state to alight state, for example, from the end point 1404 to the start point1402, a relationship between a color coordinate or color dimension andstates of transmittance may be reversed, as the electrochromic devicemay sequentially pass through the fourth stage 1412, the third stage1410, the second stage 1408, and the first stage 1406. In some examples,a color coordinate change of the electrochromic device may exhibit ahysteresis effect when transitioning between a dark state and a lightstate, compared to a color coordinate change of an electrochromic devicetransitioning between a light state and a dark state.

In some embodiments, a controller, such as the controller 1205 or thecontroller 1305, may determine a current color coordinate of theelectrochromic device (e.g., 1200 or 1300), using information of a stateof transmittance of the electrochromic device. For example, thecontroller may determine a location on a graph (e.g., graph depictingthe relationship 1400 of FIG. 14) corresponding to the state oftransmittance, and determine the current color coordinate from the stateof transmittance, in lab coordinates. For instance, the controller maydetermine that the state of transmittance corresponds to the first stage1406, or a point within the first stage 1406, and determine acorresponding color coordinate from the state of transmittance.

In some embodiments, a spectrometer and/or a tristimulus colorimeter mayindividually determine colors and levels of transmittance ortransmittance states of the electrochromic device simultaneously. Thespectrometer may determine a spectral power distribution of a lightintensity over a range of wavelengths. The spectrometer or the tristimulus colorimeter may determine color information by integrating thespectral power distribution with CIE color-matching functions. Thespectrometer or the tristimulus colorimeter may transform obtained colorcoordinates (x,y) into (u,v) or lab color spaces.

FIG. 15 shows an exemplary tristimulus colorimeter 1500. The tristimuluscolorimeter 1500 may comprise color filters 1502 and photodetectors 1504respectively coupled with the color filters. The color filters 1502 maycomprise a blue color filter, a green color filter, and a red colorfilter. The photodetectors 1504 may determine a light intensity of eachof the respective color filters 1502. The photodetectors 1504 maycomprise silicon diodes.

FIG. 16 is an illustration showing a schematic of an electrochromicdevice 1600 (e.g., a smart window), consistent with exemplaryembodiments of the present disclosure. The electrochromic device 1600may include two layers of glass 1601, two adhesive layers 1602, anelectrochromic film 1603, one or more electric wires 1604, a controller1605, and a solar cell 1606 integrated into the electrochromic device1600. In some embodiments, the solar cell 1606 may be configured tosupply energy to the controller 1605 by converting acquired solar energyinto electric energy. In some examples, the converted electric energymay be stored in a power storage unit such as a battery or a capacitor.The solar cell 1606, in addition to generating energy, maysimultaneously detect a light intensity. In some embodiments, the solarcell 1606 may detect the light intensity based on an amount of currentgenerated by the solar cell 1606. In some examples, the solar cell 1606may detect the light intensity based on a relationship between thecurrent generated and the light intensity, and/or based on apredetermined relationship between the current generated and the lightintensity. In some embodiments, the current generated by the solar celllinearly depends on the light intensity. In some examples, the solarcell 1606 may transmit information of or a signal indicating the lightintensity to the controller 1605.

The controller 1605 may consume the stored electric energy in the powerstorage unit, for example, when an amount of converted electric energygenerated by the solar cell 1606 is inadequate to operate the controller1605. In response to receiving the information of or a signal indicatingthe light intensity, the controller 1605 may adjust a transmission stateand/or a color of the electrochromic device 1600 by injecting orwithdrawing a certain amount of power to the electrochromic device 1600.In some examples, the controller 1605 may adjust a level of transmissionto be inversely related to the detected light intensity by the solarcell 1606. If the detected light intensity increases, the controller1605 may reduce a level of transmission through the electrochromicdevice 1600. If the detected light intensity decreases, the controller1605 may increase a level of transmission through the electrochromicdevice 1600.

The controller 1605 may further be configured to monitor and adjust acolor of the electrochromic device 1600, similar to the implementationof the controller 1205 as described with respect to FIG. 12A. In someembodiments, the controller 1605 may be laminated between the two layersof glass 1601.

The two layers of glass 1601 may be implemented as the two layers ofglass 1201 of FIG. 12A. The two adhesive layers 1602 may be implementedas the two adhesive layers 1202 of FIG. 12A. The electrochromic film1603 may be implemented as the electrochromic film 1603 of FIG. 12A. Theone or more electric wires 1604 may be implemented as the one or moreelectric wires 1204 of FIG. 12A.

FIGS. 17-18 are diagrams illustrating a self-contained and self-poweredcontroller powered by an energy generator such as a solar cell. In FIG.17, an energy generator, such as a solar cell 1706, may supply power tothe controller 1705. The solar cell 1706 may be implemented as the solarcell 1606 of FIG. 16. The controller 1705 may be implemented as thecontroller 1605 of FIG. 16. As shown in FIG. 17, the controller 1705 mayinclude a power storage unit 1701, a power converter 1702, a poweroutput control 1703, and a signal receiver 1704. The power storage unit1701 may be a battery or a capacitor. The power converter 1702 mayconvert input power from the power storage unit 1701 to a power requiredby or usable by the signal receiver 1704 and the power output control1703. Thus, in some embodiments, the power output control 1703 and thesignal receiver 1704 may receive power indirectly from the solar cell1706. An amount of power received by the power output control 1703 andthe signal receiver 1704 may not completely depend upon an amount oflight captured by the solar cell 1706. The power output control 1703 maybe configured to supply power to an electrochromic device such as theelectrochromic device 1600, for example, in response to information fromthe signal receiver 1704. The signal receiver 1704 may be configured toreceive information of or signals indicating detected light intensity,level of transmission of the electrochromic device, and/or a color ofthe electrochromic device. The power output control may be configured tosupply power in an amount based on the information of or the signalsreceived from the signal receiver 1704, similar to mechanismsimplemented in FIG. 16. In some embodiments, an active light receivingportion of the solar cell 1706 faces toward a light source such assunlight. In some embodiments, the solar cell 1706 may determine anincident angle of light that strikes an active light receiving portionof the solar cell 1706. The solar cell 1706 may adjust its orientationwith respect to the light source to maximize an amount of light thatstrikes an active light receiving portion of the solar cell 1706, forexample, when the incident angle of light is 90 degrees.

In FIG. 18, an energy generator, such as a solar cell 1806, may supplypower to the controller 1805. The solar cell 1806 may be implemented asthe solar cell 1606 of FIG. 16. In some embodiments, the solar cell 1806may generate power while simultaneously determining a light intensity.In some embodiments, the solar cell 1806 may detect the light intensitybased on an amount of current generated by the solar cell 1806. In someexamples, the solar cell 1606 may detect the light intensity based on arelationship between the current generated and the light intensity,and/or based on a predetermined relationship between the currentgenerated and the light intensity. In some embodiments, the currentgenerated by the solar cell linearly depends on the light intensity. Insome examples, the solar cell 1806 may transmit information of or asignal indicating the light intensity to the controller 1805,specifically, to a signal receiver such as the signal receiver 1804, asdescribed below.

The controller 1805 may be implemented as the controller 1605 of FIG.16. As shown in FIG. 18, the controller 1805 may include a power storageunit 1801, a power converter 1802, a power output control 1803, and asignal receiver 1804. The power storage unit 1801 may be a battery or acapacitor to receive stored electric power from the solar cell 1806,simultaneously with the solar cell 1806 transmitting information of or asignal indicating the light intensity to the signal receiver 1804. Thepower converter 1802 may convert input power from the power storage unit1801 to a power required by or usable by the signal receiver 1804 andthe power output control 1803. Thus, in some embodiments, the poweroutput control 1803 and the signal receiver 1804 may receive powerindirectly from the solar cell 1806. An amount of power received by thepower output control 1803 and the signal receiver 1804 may notcompletely depend upon an amount of light captured by the solar cell1806. The power output control 1803 may be configured to supply power toan electrochromic device such as the electrochromic device 1600, forexample, in response to information from the signal receiver 1804. Thesignal receiver 1804 may be configured to receive information of orsignals indicating detected light intensity, level of transmission ofthe electrochromic device, and/or a color of the electrochromic device.In some embodiments, the signal receiver 1804 determines an amount ofpower to be supplied to the electrochromic device based on the currentgenerated by the solar cell 1806 or a current density transmitted fromthe solar cell 1806 to the signal receiver 1804. In some embodiments,the signal receiver 1804 may transmit the determined amount of power tothe power output control 1805. The power output control 1805 may beconfigured to supply power in an amount based on the information of orthe signals received from the signal receiver 1804, similar tomechanisms implemented in FIG. 16. In some embodiments, an active lightreceiving portion of the solar cell 1806 faces toward a light sourcesuch as sunlight. In some embodiments, the solar cell 1806 may determinean incident angle of light that strikes an active light receivingportion of the solar cell 1806. The solar cell 1806 may adjust itsorientation with respect to the light source to maximize an amount oflight that strikes an active light receiving portion of the solar cell1806, for example, when the incident angle of light is 90 degrees.

In this disclosure, we present methods of changing optical states ofelectrochromic materials with constant voltage driving and constantcurrent driving. It should also be well understood that a combination ofvoltage driving and current driving, pulsed voltage driving and currentdriving, combination of pulsed and DC driving, etc. can also be employedto change electrochromic materials to a desired optical state. As longas a certain amount of charges is injected into or extracted from anelectrochromic material, the optical state of the electrochromicmaterial can be adjusted accordingly.

The foregoing description of the present invention has been provided forthe purposes of illustration and description. It is not intended to beexhaustive or to limit the invention to the precise forms disclosed. Thebreadth and scope of the present invention should not be limited by anyof the above-described exemplary embodiments. Many modifications andvariations will be apparent to the practitioner skilled in the art. Themodifications and variations include any relevant combination of thedisclosed features. The embodiments were chosen and described in orderto best explain the principles of the invention and its practicalapplication, thereby enabling others skilled in the art to understandthe invention for various embodiments and with various modificationsthat are suited to the particular use contemplated. It is intended thatthe scope of the invention be defined by the following claims and theirequivalence.

What is claimed is:
 1. An electrochromic device, comprising: two layersof glass; an electrochromic film disposed between the two layers ofglass; a sensor; and a controller coupled to the electrochromic film andthe sensor, wherein: the sensor is configured to: detect a transmittanceor spectrum of the electrochromic film, and send a signal of thedetected transmittance or spectrum to the controller; and the controlleris configured to: determine a color of the electrochromic film at leastbased on the signal, and inject an amount of electric charges into theelectrochromic film or remove an amount of electric charges from theelectrochromic film based on the determined color.
 2. The electrochromicdevice of claim 1, wherein the sensor comprises a spectrometerconfigured to determine a spectral power distribution of a lightintensity over a range of wavelengths.
 3. The electrochromic device ofclaim 1, wherein: the sensor comprises a tristimulus colorimetercomprising three color filters and a plurality of three correspondingphotodiodes.
 4. The electrochromic device of claim 1, wherein: thesensor comprises an active sensing portion configured to face theelectrochromic device and not face direct sun light and configured todetect a reflected spectrum of the electrochromic film; and the color ofthe electrochromic film comprises a reflected color of theelectrochromic film.
 5. The electrochromic device of claim 1, wherein:the sensor comprises an active sensing portion configured to face theelectrochromic device and face direct sun light and configured to detecta transmitted spectrum of the electrochromic film; and the color of theelectrochromic film comprises a transmitted color of the electrochromicfilm.
 6. The electrochromic device of claim 1, wherein the controller isconfigured to inject an amount of electric charges into theelectrochromic film or remove an amount of electric charges from theelectrochromic film based on the determined color, until a differencebetween the color and a target color of the electrochromic film is lessthan a threshold.
 7. The electrochromic device of claim 6, wherein: thetarget color of the electrochromic device is a color or target color ofa different electrochromic film in a different electrochromic device;and the different electrochromic device is in a same room, house,building, or dwelling as the electrochromic device.
 8. Theelectrochromic device of claim 6, wherein the target color is a color ofthe electrochromic film when the electrochromic film is in (i) a dark orlight state and (ii) an undegraded state.
 9. The electrochromic deviceof claim 1, wherein, to determine the color of the electrochromic filmbased on the signal, the controller is configured to: determine a levelof transmittance or a transmittance state of the electrochromic filmbased on the signal; and determine the color of the electrochromic filmbased on (i) the level of transmittance or the transmittance state and(ii) a relationship between color coordinates and the level oftransmittance or the transmittance state.
 10. The electrochromic deviceof claim 9, wherein, to inject the amount of electric charges into theelectrochromic film or remove the amount of electric charges from theelectrochromic film based on the determined color, the controller isconfigured to: determine an amount of adjustment to be applied to thecolor based on a rate of change of the color relative to a change in thelevel of transmittance or the transmittance state.
 11. Theelectrochromic device of claim 1, wherein, to inject the amount ofelectric charges into the electrochromic film or remove the amount ofelectric charges from the electrochromic film based on the determinedcolor, the controller is configured to apply a DC voltage or DC currentto the electrochromic film.
 12. The electrochromic device of claim 1,wherein, to inject the amount of electric charges into theelectrochromic film or remove the amount of electric charges from theelectrochromic film based on the determined color, the controller isconfigured to apply a pulse voltage or pulse current to theelectrochromic film.
 13. An electrochromic device, comprising: twolayers of glass; an electrochromic film disposed between the two layersof glass; a solar cell; and a controller coupled to the electrochromicfilm and the solar cell, wherein: the solar cell is configured to:simultaneously supply energy to the controller and detect a lightintensity of external light based on an amount of current generated bythe solar cell, and transmit a signal or information of the lightintensity to the controller; and the controller is configured to adjusta level of transmission, a transmission state, or a color of theelectrochromic film based on the light intensity or a change in thelight intensity.
 14. The electrochromic device of claim 13, wherein: thecontroller comprises a power storage, a power converter, and a signalreceiver; the power storage is coupled to the solar cell and isconfigured to storage power from the solar cell; the power converter iscoupled to the power storage and is configured to convert the power fromthe power storage; and the signal receiver is coupled to the powerconverter and is configured to receive the converted power from thepower converter.
 15. The electrochromic device of claim 14, wherein thesignal receiver is further coupled to the solar cell directly andconfigured to receive the signal or information of the light intensity.16. The electrochromic device of claim 14, further comprising a poweroutput control configured to receive power indirectly from the solarcell and supply power to the electrochromic film.
 17. The electrochromicdevice of claim 16, wherein the power output controller is configured toinject an amount of electric charges into the electrochromic film orremove an amount of electric charges from the electrochromic film. 18.The electrochromic device of claim 17, wherein, to inject the amount ofelectric charges into the electrochromic film or remove the amount ofelectric charges from the electrochromic film, the power outputcontroller is configured to apply a DC voltage or DC current to theelectrochromic film.
 19. The electrochromic device of claim 17, wherein,to inject the amount of electric charges into the electrochromic film orremove the amount of electric charges from the electrochromic film, thepower output controller is configured to apply a pulse voltage or pulsecurrent to the electrochromic film.
 20. A method, comprising: detecting,by a sensor of an electrochromic device, a transmittance or spectrum ofan electrochromic film of the electrochromic device, wherein theelectrochromic film is disposed between two layers of glass of theelectrochromic device, wherein the spectrum comprises a spectrum oflight that is transmitted through the electrochromic film or that isreflected from the electrochromic film; sending, by the sensor, a signalof the detected transmittance or spectrum to a controller of theelectrochromic device, wherein the controller is coupled to theelectrochromic film and the sensor; determining, by the controller, acolor of the electrochromic film at least based on the signal; andinjecting, by the controller, an amount of electric charges into theelectrochromic film or removing, by the controller, an amount ofelectric charges from the electrochromic film based on the determinedcolor.